Accurate protection of single-phase grounding fault section in distribution network
Medium-voltage power distribution network in China is dominated by small-current grounding systems,with single-phase-ground faults most.Existing single-phase-to-ground protection faces the challenges of difficult to discriminate fault sections,insufficient reliability caused by interference,and low sensitivity for faults through high resistance.This paper proposes a precise protection scheme for single-phase-to-ground fault section in power distri-bution network using only local fault information.The scheme is based on the characteristics of phase current chan-ges before and after the fault to startup of protection relay,combined with the characteristics of the voltage and zero-sequence current change and the time delay to selectively trip the circuit breaker at the power-side of faults;and in accordance with the trip time delay of opposite-end protection relay and circuit breaker,combined with the three-phase voltage change to trip the circuit breaker at the load side of the ground fault section using local information.Simulation results show that the proposed scheme can operate accurately without communication and even for faults through high resistances.
distribution networksingle-phase-to-ground faultfault section isolation
万方数据
维普
